Method and apparatus for batch impregnation of porous articles



Nov. 28, 1961 EWING ET AL METHOD AND APPARATUS FOR BATCH IMPREGNATION OF POROUS ARTICLES 3 Sheets-Sheet l Filed July 1 lll ll l lll l LLOYD EWING REID Ewlms Nov. 28, 1961 L. EWING ET AL METHOD AND APPARATUS FOR BATCH IMPREGNATION OF POROUS ARTICLES 5 Sheets-Sheet 2 Filed July 1, 1958 P/ TCH SUP/ L Y Q a A w v /w 1 M W NNWSQW Z c w. \QQQSW m T .kxwk M w m s SUPPL Y M A W mm /M m N T0 VACUUM 5 Y5 TEN METHOD AND APPARATUS FOR BATCH IMPREIGNATION OF POROUS ARTICLES Nov. 28, 1961 EWING ET AL P/ TC H SUP/ L Y M u wuQAGm w w l c kwmk 1 m m5 r5 1 TC/-/ SUPPL Y w W T a DE fl mmR nth 3,010,847 METHOD AND APPARATUS FQR BATCH IM- PREGNATION F POROUS ARTKCLES Lloyd Ewing, Milwaukee, Wis, Reid Ewing, Huntington,

W. Va., and Earl Hahn, Milwaukee, Wis., assignors to McGraw-Edison Company, Milwaukee, Wis, 21 corporation of Delaware Filed July 1, 1953, Ser. No. 768,512 7 Claims. (Cl. 11794) (Filed under Rule 47(b) and 35 USA). 118) This invention relates in general to a method and apparatus for saturating fibrous or other porous articles with a bituminous saturant.

More particularly, this invention relates to a method and apparatus for saturating fibrous or other porous conduits employed to conduct and protect underground cables, telephone lines, electric lights and other conductors, and for the formation of water pipes, drain pipes, etc, to render the latter substantially waterproof to abrasion or corrosion and conditions encountered above or underground by fibrous conduit. While as above stated, the invention is particularly directed to the saturation of fibrous conduit, it is understood that it may be employed to saturate any small fibrous or other articles requiring impregnation.

The articles to be saturated may, of course, be prepared in any known manner. In the case of fibrous bases for tubes, newsprint or paper pulp, or other fibrous material may be beaten in the usual paper heaters and the resulting stock screened and then pumped to paper machines and there formed into a wet sheet. Paper tubes may be formed by winding a wet sheet around a cylindrical or other shaped tube or mandrel to produce a wet conduit or tube of proper thickness. This conduit may be dried in kilns or ovens to remove the major portion of the moisture content. The fibre base may, of course, also be prepared in any other known manner. The tubes are made in several sizes commonly varying between two and six inches in internal diameter and having wall thickness of approximately /4 inch to /2 inch depending upon internal diameter and use, and are made in five, eight and ten foot lengths. The wall thickness of the tubes may, of course, be greater or less than those aforestated and the other dimensions may also vary.

Porosity or absorptive characteristic of the walls of fibrous conduits may vary within wide limits from a very dense wall of a density corresponding to hardwood and exceedingly difiicult to saturate with low carbon water gas tar pitch or even with other water proofing material to a porous open wall similar in density to that of roofing felt which will readily absorb bituminous saturants. Various types of saturants may be used, for example, coal tar pitch, gas tar pitch, asphalt, cutback pitch, blended pitch or other water proofing material may be used as suitable and desired.

, It is an object of this invention to provide a novel method and apparatus for saturating fibrous conduit or other articles which include a novel double container batch type impregnator.

It is a further object of this invention to provide a novel method and apparatus which includes apparatus which is easy to operate, requires very little room to install in original installation, and is otherwise well adapted to manufacturing operations.

A further object of this invention is to provide a double tank apparatus as above set forth which requires no pressure differential on the impregnation tank whereby the impregnation tank may be made of much thinner gauge material which can considerably reduce the original cost.

It is a further objectof this invention to provide apparatus which has less exposure to heat losses so that 3,51%,847 Patented Nov. 28, 1961 2 the pitch or other impregnant may be kept at a higher temperature at less cost.

It is a further object of this invention to provide a novel float system to automatically actuate the valve mechanism to provide replenishment of the saturant by automatic refilling of the storage tank from a supply tank exterior thereof.

It is a further object of this invention to provide a novel apparatus of the type aforestated which contains an impregnation tank disposed within a storage tank in a manner to afiord considerable foam capacity while maintaining the above described advantages.

It is a further object of this invention to provide an apparatus of the type aforementioned which has a power I actuated cover for the storage tank which affords entry to the impregnation tank to provide access for the normal working operation as well as access for cleaning and maintenance of both tanks.

It is a further object of this invention to provide an apparatus wherein an outlet from the storage tank leading to an evacuation pump apparatus may be disposed in the storage tank at a point spaced away from the open top of the inner impregnation tank to prevent excessive entrainment of so-called pitch foam.

The novel features that are characteristic of the invention are set forth with particularity in the appended claims. The invention itself, both as to its organization and its method of operation, together with additional objects and advantages thereof will best be understood by the following description of specific embodiments when read in connection with the accompanying drawings in which:

FIG. 1 is a front elevational view, a portion of which is in section showing the portions of the novel double tank batch impregnator apparatus;

FIG. 2 is a top view of the apparatus shown in FIG. 1;

FIG. 3 is a sectional view along lines 33 of FIG. 1;

FIG. 4 is a view along lines 4 -4 of FIG. 1;

FIG. 5 is a semidiagrammatic view of the apparatus in FIGS. 1-4 along with other components showing the relative position of the parts prior to the filling of the storage tank of the double tank batch apparatus with impregnant;

FIG. 6 is a semidiagrammatic view similar to FIG. 5 showing the relative position of the components during the filling operation of the storage tank;

FIG. 7 is a semidiagrammatic view similar to FIGS. 5 and 6 showing the relative position of the parts during actual impregnation of the porous articles;

FIG. 8 is a semidiagrammatic view similar to FIGS.

5-7 showing the relative position of the parts and the direction of movement of the impregnant just prior to removal of the impregnated articles; 7

FIG. 9 is a fragmentary semidiagrammatioview similar to FIGS. 5-8 showing the novel float operation for auto-- matic refilling of the storage'tank upon attainment of a predetermined impregnant level within the storage tank.

Referring now'to FIG. 1 of the drawings, the double tank batch type impregnator 12 may be generally cylinthat all the dimensions referred to are intended to be illustrative rather than limiting. A generally annular base 14 may be provided to maintain the double tank structure 12 in the upright position, said base being fixedly mounted by suitable bolts to the foundation 13. Other types of bases may be provided if desired.

, storage tank.

The double tank batch impregnator 12 essentially comprises an outer tank 15 which may be referred to as a storage tank and a smaller inner tank 16 which may be referred to as the impregnation tank. The storage tank 15 is formed with a closed bottom end 17-and an open top end 18, the latter being sealingly closed by a movable cover 19. The cover 19 has automatic cover opening means 20 here shown in the form of an air' cylinder mechanism, but it is apparent-that other" forms of auto matic opening devices as suitable and desired may be used. Suitable heat insulation "means 11, for examplepmagnes'ia block is disposed'in' surrounding relation to the outer tank 15 for reasons which will later be explained. 3 A support structure 21 is fixed firmly to the sidewalls of thetank 15 near the bottom 17 to support the inner impregnation tank 16. The impregnation tank 16 is also cylindrical in shape having a closed bottom end 16a and an open upper end 22 which is adapted to receive'the basket or other container means 55 which holds the articles such as conduit or pipe which are to be impregnated. The tank 16 is offset axially from tank 15 so that the.sidewalls are in contact with one another (best shown in FIGS. 1 and 3) which aids in mounting as well as leaving room for access for maintenance men and the'like for cleaning and maintenance of both of tanks 15 and 16.

It will be noted that the impregnation tank 16 may be considerably smaller in diametertapproximately 6 feet) as compared tothe storage tank 15. The chamber or area 23 not taken up'by tank 16 within the storage tank 15 is of sufficient capacity for storage of the impregnant and also of a size to give the desired foam capacity as shall be explained. The impregnationtank lti'may be formed of a relatively light gauge metal ascompared to the outer tank 15 inasmuch as the inner tank does not have to withstand pressure differentials imposed upon the original cost.

.-Each of the tanks 16 and 15 are'formed with an aperture 24a, 25a near the respective bottoms 16a, 17 of the tanks, said apertures being connected to suitable pipes leading to the exterior of the storage tank 15 as shown in FIGS. 1, 3 and 4 of the drawings. 7 As shown, the pipe from tank 16 extends through thesidewall of tank 15 and terminates in a fitting 24 which'serves as both an inlet and outlet to impregnation tank 16. The pipe leading from aperture 25a extends through the base 11 terminating in a fitting 25 which serves as both an inlet and outlet to tank 15. Heating coils 26 and 27 are disposed in storage chamber 23 to maintain the impregnant ata standby temperature sufiicient to afford easy movement thereof through therest of the system yet to be described. Other types of heating means suchas heating coils in contact with metal wall of tank 15 could be used if desired. The heating coils '26 and 27 are attached by suit-- able inlets such as 28 and outlets such as 29 to a heat source supply 31 shown semidiagrammatically in FIGS. -9.

A vacuum pump (not shown) is attached to the storage chamber 23 by an outlet 30 which extends through the sidewall of tank 15 at a point spaced from the inner impregnation tank 16 as shown in FIG. 3 of the drawings. The outlet 30 also may be placed in the cover 19 if desired, the important consideration being that it be at the upper end of the tank 15 and spaced from the edges of the open end 22 of tank 15 to prevent excessive entrainment of foam during the impregnation operation. If desired, shielding means such as a baffie plate or the like (not shown) can be interposed adjacent the outlet 30 to help contain the foam. 7

posed in the system shown semidiagrarnmatically in FIGS. 5-9 inclusive. Assume the conditions are as shown in FIG. 5 of the drawing, i.e., the storage chamber 23 being empty, for example, just after a cleaning ofthe This results in a substantial saving in tion shown in. FIG. 7 of the drawings.

entire device or when it is down for maintenance or repairs and/ or for other suitable reasons and the impregnant such as coal tar pitch is located at a suitable storage supply 32. Prior to starting the impregnation system in operation, the impregnant is pumped to the storage chamber 23 of tank 15 of a pump 33 through suitable conduits 34, 35, 36, 37 and 33 as shown in FIG. 6 of the drawings. The cover 19 is generally closed during this operation to save on heat and because of deleterious fumes from the impregnant which are unpleasant to operating personnel." Valve members 39 and 4t) controlthe flow of fluid impregnant to the chamber 23 and are located between portions of conduit 35, 36 and 36, 37 respectively. As shown in FIG. 6' the pitch impregnant may be pumped into chamber 23 until it reaches a level 50 somewhat below the top 22 of the impregnation tank 16. Valve 39 is. then closed. 7

Assuming a sutficient standby temperature of the pitch impregnant, the system is now ready for the normal impregnation cycle. The cycle starts with the opening of the cover 19 to the storage and impregnation tank, and the disposition of a basket 55 containing the oven predried porous elongated tubes or other articles to be impregnated within the impregnation tank 16. Cover 19 is then sealingly closed and valve 40 is turned to the posi- The pitch impregnant located in the storage chamber 23 is then pumped out of ehamber 23 by means of a reversible pump 417and then through a heat exchanger 42, through valve 43 ,and into the impregnation tank 16 as shown by the arrows in FIG. 7. The impregnant is heated from a standby temperature to the best impregnation temperature (approximately 340 F.) by means of the outside heat exchanger 42 thereby reducing the amount of heat that must be supplied to the system by heat source 31 while the pitch impregriant is stored in the storage chamber 23. This outside heat exchanger '42' is advantageous in cost, maintenance and suitable for heating a direct supply of impregnant from source 32 as shall be explained. The pitch impregnant upon entering the impregnation tank 16 enters through suitable apertures in the basket 55 and rises upwardly until it overflows over the top edge 22 of the tank 16. Thereupon the pitch impregnant falls down the sides of the tank 16 to the level of the pitch as shown in FIG. 7 for recirculation through the heat exchanger 42 to form a continuous circulating system. If desired, the overflow of the pitch impregnant can be controlled'by means of a piping arrangement (not shown).

A vacuum is now drawn and released upon the storage tank chamber 23 by means of a vacuum pump system (not shown) to cause complete saturation of the porous articles disposed in the basket. A vacuum may be drawn and released as many times as necessary in accordance with established procedure as well understood in the art. Inherent in this impregnation system is a foaming action.

This is caused by many things including the recirculating The novel double batch impregnator 12 may be dis- 7 movement of the pitch as well as the removal of gas and water vapor trapped in the porous tubes or other articles. It will be noted that there is substantial foam capacity for this system as shown semidiagrammatically in FIG. 7, said foam capacity being very desirable for practical operating characteristics.

After completion of the impregnation of the articles, valve member 43 remains in the position shown in FIG. 8 and the impregnation tank 16 is drained by the pump 41 which pumps the impregnant back into the storage chamber 23 However, since the elongated porous articles have absorbed a portion of the pitch impregnant, the pitch level is now at point 50' rather than 50;, the original starting level. The cover 19 is now reopened and the basket 55 containing the elongated porous articles is re- I moved from the impregnation tank and placed in the may be disposed in impregnation tank and the same procedure will be followed.

In the original filling of chamber 23 of tauk 16 from supply 32, it is sometimes desired to run the pitch impregnant through the heat exchanger 42 to raise the temperature to a higher level. To accomplish this, valve 39 remains as shown in FIG. 6, whereas valve 40 is rotated 90 to the left and valve 43 is rotated 90 to theright. The impregnant will now enter chamber 23 by flowing through conduit or pipe 48 as shown by the dotted arrows in FIG. 6.

The system shown may be operated with a continuous replenishment of the pitch impre nant or may be operated such that after the occurrence of, for example, five or more impregnation cycles, the system may be refilled through valves 39 and 40 as described earlier. This depends upon the desired characteristics'at the precise location of the impregnation apparatus. The particular apparatus shown has a bypass pipe 44 from the pitch supply 32 leading'through a valve 45 and a valve 43so-that during pumping of the impregnant from the storage chamber 23 during an impregnation cycle, additional pitch may be brought in from the pitch supply 32 and brought through the heat exchanger 42. This is accomplished by a float 46 which is actuatingly attached to a suitable switch 47 which actuates the valve 45 and the pump33. The refinement of the float operated switch 47 and the bypass conduit 44 and valve 45 are not absolutely necessary to the system but do provide for automatic replenishment of the pitch supply when that function is desired.

In some applications it is desired that pump 41 be run in a single direction or be a single directional pump rather than reversing the operation thereof as aforedescribed. In the latter event, two additional pieces of conduit or pipe 51 and 52 may be interposed between conduit or pipes 48-49 and 53-36 respectively as shown in FIG. 8. An additional valve 54 may be placed in conduit or pipe 48 below the connection of conduit 51 to take care of back pressure if desired. Then when it is desired to empty tank 16, valve 43 is moved 180 from the position shown in FIG. 8 and valve 4%} is moved to 90 to the left from the position shown in FIG. 8; The emptying flow will then be as shown by dotted arrows in FIG. 8.

Although specific embodiments of the invention have been shown and described, it is with full awareness that many modifications thereof are possible. The invention therefore is not to be restricted except insofar as is necessitated by the prior art and by the spirit of the appended claims.

What is claimed as the invention is:

1. Apparatus for saturating elongated fibrous articles comprising a large cylindrical thermally insulated first tank forming a storage chamber and having a cover detachably sealingly mounted thereon, both said tank and said cover being formed of thick gauge material adapted to withstand high pressure differentials between the interior and exterior of said chamber, a second cylindrical tank having an open top end portion and formed of relatively thin gauge material and adapted to normally contain impregnating material and fibrous articles, said second cylindrical tank being of smaller diameter than said first tank and disposed in axially offset relation within said first tank, vacuum producing means, vacuum outlet means from said storage tank chamber disposed at a point spaced away from said second tank, said vacuum outlet means being attached to said vacuum producing means, heat producing means internally of said first tank and exterior of said second tank, passageway means communicating said first tank and second tank, reversible pump means in said passageway means, and heat exchanger means in said passageway means, whereby imthrough said passageway' means including said heat exchanger to raise-the temperature thereofenrouteto'said pregnant may be stored and maintained at a standby t temperature in said storage chamber exterior of said second tank and then the impregnant may be pumped impregnation tank, the impregnant during pumping: spillage chamber-for recirculation through said: passageway means.

2. Apparatus for impregnating elongate fibrous articles comprising outer enclosure means defining a sealed storage chamber, support means disposed within said storage chamber, a second enclosuremeans mounted on said support means to provide a separate impregnation-chamber within said storage chamber, said second enclosure means adapted to contain said fibrous articles and impregnating material, access means through said sealed storagev chamber affording entry to said'impregnation chamber, and passageway means having a portion external to both of said enclosure means and providing communication between said storage chamber and said impregnation chamber to afford ingress and egress of the impregnant.

3.'Apparatus for impregnating elongate fibrous articles comprising an outer tank defining a sealed pitch storage chamber, a support structure disposed near the bottom of and within said storage chamber, a second tank mounted on said support structure to provide a separate impregnation chamber within said storage chamber so that said fibrous articles may be immersed in impregnant, a movable cover providing access through said sealed storage chamber and affording entry to said impregnation chamber, and passageway means having a portion external to both of said enclosure means and providing communication between said storage chamber and said impregnation chamber to afford ingress and egress of the pitch impregnant.

4. Apparatus for impregnating elongate fibrous articles comprising outer cylindrical tank means defining a sealed storage chamber, a second cylindrical tank means having an open end and axially offset from and disposed within said firsttank means to provide a separate impregnation chamber within said storage chamber so that said fibrous articles may be immersed in impregnating fluid, removable cover means for said sealed storage chamber affording entry to said open end of said second tank means to afford loading of said impregnation chamber, and passageway means having a portion external to both of said enclosure means and providing communication between said storage chamber and said impregnation chamber to afford ingress and egress of the impregnant.

5. Apparatus for saturating elongated fibrous articles comprising a large cylindrical thermally insulated first tank forming a storage chamber and having a cover detachably sealingly mounted thereon, both said tank and said cover being formed of thick gauge material adapted to Withstand high pressure differentials between the interior and exteriorof said chamber, a second cylindrical tank having an open top end portion and formed of relatively thin gauge material and adapted to serve as a receptacle for imprcgnant so that said fibrous articles may be immersed therein, said second cylindrical tank being of smaller diameter than said first tank and disposed in axially offset relation within said first tank, vacuum producing means, vacuum outlet means from said storage tank chamberdisposed in spaced relation to said second tank, said vacuum outlet means being attached to said vacuum producing means, heat producing means internally of said first tankland exterior of saidsecond tank, impregnant storage means spaced from'said first tank, passageway means communicating said first tank, second tank and impregnant storage means, reversible pump means in said passageway means, heat exchanger means in said passageway means, valve means in said passageway means and float means-in said first tank connected to said valve means to cause, under predetermined conditions, openingof said valve means to afford movement of impregnant to said first tank from said storage means.

6. The process of saturating oven-pre-dried tubes with a pitch impregnant While said tubes are disposed in an impregnation tank which is in turn disposed within a pitch filled storage tank, comprising the steps of disposing said tubes within said impregnation tank, sealing said storage tank, pumping pitch impregnant from said storage tank through a heating means to said impregnation tank, filling said impregnation tank with pitch impregnant from said storage tank to fully immerse said tubes and to substantially empty said storage tank to provide substantial pitch foam capacity immediately adjacent said impregnation tank, continuing to pump impregnant to said impregnation tank to cause said impregnant in said impregnation tank to spill over the sides thereof into said storage tank for recirculation, drawing a vacuum on the storage tank to remove any residual vapors from the tubes to afford complete saturation thereof, releasing the vacuum, removing impregnant from the impregnation tank to the storage tank, unsealing the storage tank, and removing the pitch saturated impregnated tubes'from said impregnation tank.

7. The process of saturating oven pre-dried tubes with a heated pitch impregnant while said tubes are disposed in an impregnation tank which is in turn disposed within a pitch filled storage tank, comprising the steps of disposing said tubes within said impregnation tank, sealing said storage tank, pumping pitch impregnant from said storage tank through a heating means to said impregnation tank, filling said impregnation tank with pitch impregnant from said storage tank to fully immerse said tubes and to substantially empty said storage tank to provide substantial pitch foam capacity immediately adjacent said impregnation tank, continuing to pump impregnant to said impregnation tank to cause said impregnant in said impregnation tank to spill over the sides thereof into said storage tank for recirculation, drawing a vacuum on the storage tank to remove any residual vapors from the tubes to aiford complete saturation thereof, releasing the vacuum, reversing the pumping operation to empty the impregnation tank and to refill the storage tank, and removing the pitch saturated impregnated tubes from said impregnation tank.

References Cited in the file of this patent UNITED STATES PATENTS 1,864,674 Schur June 28, 1932 1,920,191 Ford et a1. Aug. 1, 1933 1,986,319 Bongrand et a1. Jan. 1, 1935 1,988,955 Nehmert Jan. 22, 1935 2,012,968 Miller Sept. 3, 1935 2,012,970 Miller Sept. 3, 1935 2,016,060 Strauch Oct. 1, 1935 2,096,888 Emberg Oct. 26, 1937 2,303,257 Campbell et a1 Nov. .24, 1942 2,478,439 Liedtke Aug. 9, 1949 2,529,699 Lach Nov. 14, 1950 2,628,173 Fair Feb. 10, 1953 

1. APPARATUS FOR SATURATING ELONGATED FIBROUS ARTICLES COMPRISING A LARGE CYLINDRICAL THERMALLY INSULATED FIRST TANK FORMING A STORAGE CHAMBER AND HAVING A COVER DETACHABLY SEALINGLY MOUNTED THEREON, BOTH SAID TANK AND SAID COVER BEING FORMED OF THICK GAUGE MATERIAL ADAPTED TO WITHSTAND HIGH PRESSURE DIFFERENTIALS BETWEEN THE INTERIOR AND EXTERIOR OF SAID CHAMBER, A SECOND CYLINDRICAL TANK HAVING AN OPEN TOP END PORTION AND FORMED OF RELATIVELY THIN GAUGE MATERIAL AND ADAPTED TO NORMALLY CONTAIN IMPREGNATING MATERIAL AND FIBROUS ARTICLES, SAID SECOND CYLINDRICAL TANK BEING OF SMALLER DIAMETER THAN SAID FIRST TANK AND DISPOSED IN AXIALLY OFFSET RELATION WITHIN SAID FIRST TANK, VACUUM PRODUCING MEANS, VACUUM OUTLET MEANS FROM SAID STORAGE TANK CHAMBER DISPOSED AT A POINT SPACED AWAY FROM SAID SECOND TANK, SAID VACUUM OUTLET MEANS BEING ATTACHED TO SAID VACUUM PRODUCING MEANS, HEAT PRODUCING MEANS INTERNALLY OF SAID FIRST TANK AND EXTERIOR OF SAID SECOND TANK, PASSAGEWAY MEANS COMMUNICATING SAID FIRST TANK AND SECOND TANK, REVERSIBLE PUMP MEANS IN SAID PASSAGEWAY MEANS, AND HEAT EXCHANGER MEANS IN SAID PASSAGEWAY MEANS, WHEREBY IM- 